Conventionally, as a headphone device which is an example of a head-mounted wearable speaker device, there has been widely used the headphone device that is used in a state of being mounted on the head of a listener, and converts an audio signal expressing a reproduced voice of a CD (Compact Disc) to a sound (hereinafter, referred to as a reproduced sound) so as to make the listener capable of listening to the reproduced sound.
In the headphone device generally used, a speaker unit that generates the reproduced sound is positioned in the vicinity of the front of an entrance of an external acoustic meatus of the listener. Although a sound is allowed to reach an eardrum directly from the speaker unit to possibly improve sound quality, a sound image is localized in the head of the listener and this has provided an unnatural impression to the listener.
For the above reason, there has been devised the headphone device in which the speaker unit is positioned at a location somewhat distant from the entrance of the external acoustic meatus (ear hole) and closer to a parietal region. In this manner, the sound image is localized outside the head just like a general stationary speaker to remove the unnaturalness. At the same time, the headphone device is made as a closed type to form enclosed space around an ear of the listener in consideration of making the listener capable of listening to a low-pitched sound sufficiently.
Pat. Document: Jpn. Pat. No. 3054295 (page 3, FIG. 1)
With respect to the headphone device with the above configuration, it has been requested to provide the listener with a sense of liberation by making the headphone device to be an open type while excellent sound quality including a sufficient low-pitched sound is maintained. However, since the speaker unit is isolated from the ear hole, the sound quality becomes deteriorated with insufficient low frequencies when nothing further than changing the closed type to the open type is carried out, and there has been a problem that the above request cannot be fulfilled.
In addition, in the headphone device with the above configuration, the speaker unit is positioned at the location somewhat distant from the entrance of the external acoustic meatus (ear hole) and closer to the parietal region. For this reason, middle-pitched and high-pitched sounds do not reach the ear hole smoothly as well, and there has been a problem that the listener is not capable of listening to the middle-pitched and high-pitched sounds at a sufficient level.